Fritziana, Mello-Leittao, 1937
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publication ID |
https://doi.org/ 10.1016/j.jcz.2022.03.003 |
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persistent identifier |
https://treatment.plazi.org/id/038F878E-FFC2-FFE6-127E-ED59FDB6FAA5 |
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treatment provided by |
Felipe |
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scientific name |
Fritziana |
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3.1. Cranial osteology of Fritziana View in CoL ( Figs. 1–3 View Fig View Fig View Fig )
Sphenethmoid. This neurocranial bone is complete and forms the anterior end of the braincase and the posterior wall of the nasal capsules. Dorsally, the anterior ends of the frontoparietals overlap the posterolateral margin of the sphenethmoid ( Fig. 1 View Fig ). The anterior margin of the sphenethmoid is overlapped ( Fr. goeldii , Fr. ohausi [ZUFRJ 12416], Fr. tonimi , Fr. izecksohni , Fr. ulei ; Fig. 1A,D,E,F View Fig ) or slightly overlapped by the nasals ( Fr. ohausi [ZUFRJ 12417, 597], Fr. fissilis ; Fig. 1B and C View Fig ). Ventrally, the neopalatines extend onto the ventrolateral surface of the sphenethmoid and are broadly separated medially ( Fig. 2 View Fig ). The parasphenoid overlaps the midventral sphenethmoid and extends to its midlength ( Fig. 2 View Fig ). The extension of leading margin of the sphenethmoid bone may lie posterior or almost posterior ( Fr. goeldii and Fr. tonimi ;
Fig. 2A,D View Fig ), at the midlength ( Fr. ohausi, ZUFRJ 12417; Fr. fissilis , Fr. izecksohni , Fr. ulei ; Fig. 2B,C,E,F View Fig ), or anterior to the vomers ( Fr. ohausi, ZUFRJ 12416 and 597). The posterior margin of the sphenethmoid lies anterior ( Fr. goeldii , Fr. ohausi , Fr. fissilis , Fr. tonimi and Fr. izecksohni ) or posterior to the midlength of the orbit ( Fr. ulei ), and it is broadly separated by cartilage from the anterior margin of the prootic.
Fused Exoccipital and Prootic. The exoccipital portions of this composite element form the posterior end of the braincase. Unfused dorso- and ventromedially, the medial separation is wider ventrally than dorsally, and the intervening cartilage is mineralized. The prootic portion forms the posterolateral walls of the braincase, and together with its cartilaginous crista parotica, the middle ear. The lateral edge of the crista parotica is invested by the otic ramus of the squamosal, and is clearly separated by cartilage from the ossified prootic in all except Fritziana goeldii , Fr. fissilis , and Fr. ulei ( Fig. 1A,C,F View Fig ). The prominent anterior epiotic eminence is about twice as long as the posterior epiotic eminence, and the angle between the two is approximately 90 ◦ ( Fig. 1 View Fig ).
Nasals. These paired dermal bones roof the nasal capsule. The long axes of the nasals are obliquely oriented on the rostrum approximately parallel to the anterolateral margin of the sphenethmoid ( Fig. 1 View Fig ). The bones have a narrow medial separation in all species except in Fritziana ohausi and Fr. tonimi ( Fig. 1B,D View Fig ), in which the medial separation between the nasals is moderate. The maxillary process of the nasal is not in contact with the pars facialis of the maxilla in Fritziana goeldii ( Figs. 1A View Fig and 3A View Fig ) and Fr. ohausi (ZUFRJ 12417) owing to differences in the configuration of the facial region of the maxilla in these taxa.
Frontoparietals. These paired, dermal bones overlie the taenia tecti marginalis, the cartilaginous margin of the frontoparietal fontanelle of the braincase. The broad separation of the narrow elements in Fritziana ohausi ( Fig. 1B View Fig ) exposes more of the fontanelle than does the moderate separation of proportionally wider frontoparietals in Fr. goeldii , F. izecksohni , F. fissilis , F. tonimi and F. ulei ( Fig. 1A View Fig ,C-F). The posterior ends invest the prootic medial to the anterior epiotic eminence ( Fig. 1 View Fig ). Depending on the widths of the frontoparietals, variable portions of the tectum synoticum (posterior margin of the frontoparietal fontanelle) are visible ( Fig. 1 View Fig ).
Parasphenoid ( Fig. 2 View Fig ). This dermal bone forms the floor of the braincase bridging the basicranial fenestra between the sphenethmoid and prootics. In species of Fritziana , the lateral margins of the cultriform process converge slightly on one another medially in the orbital region to produce an acuminate shape; the anterior end terminates on the ventral surface of the sphenethmoid at approximately the midlength of the bone. The anterior end of the cultriform process is acuminate in every taxon, but the anterior tip is irregularly acuminate ( Fr. goeldii [ZUFRJ 12964, 13066], Fr. ohausi [KU 92230]) or smoothly acuminate ( Fr. goeldii [ZUFRJ 13455], Fr. ohausi [ZUFRJ 597, 12416, 12417], Fr. fissilis , Fr. izecksohni , Fr. tonimi , Fr. ulei ). The parasphenoid alae are narrow and posterolaterally oriented beneath the otic capsule; the distal margins of the alae are rounded and terminate around the midpoint of the otic capsule, where they are broadly separated from the medial process of the pterygoid ( Fig. 2 View Fig ). The parasphenoid terminates in a triangular process anterior to the foramen magnum ( Fig. 2 View Fig ).
Neopalatines ( Fig. 2 View Fig ). These paired, arcuate, dermal bones underlie the antorbital cartilage that forms the anterior margin of optic capsule. The medial end of each neopalatine is sharp and articulates with the anterolateral margin of the sphenethmoid. The lateral end is truncate and articulates with the posterior maxillary cartilage supporting the maxilla.
Vomers. The floor of the nasal capsules is invested by these paired, dermal bones. The anterior process is curved, acuminate, and extends toward the maxilla, from which it is narrowly separated ( Fritziana fissilis , and Fr. tonimi ; Fig. 2C–E View Fig ). The process is broadly separated from the maxilla in Fr. goeldii , Fr. ohausi , and Fr. ulei ( Fig. 2A,B,F View Fig ); however, the broad separation in Fr. ulei reflects the poorly developed anterior vomerine process in this species. The prechoanal process forms the anterior and anteromedial margin of the choana and terminates in a sharp point ( Fig. 2 View Fig ). The postchoanal process of the vomers forms the posteromedial margin of the choana, and terminates in a sharp point ( Fig. 2 View Fig ). The posteromedial margins of the vomers may be separated from one another by a distance greater than the length of the palatine processes of the premaxillae ( Fr. goeldii ; Fr. ohausi ; Fr. tonimi and Fr. izecksohni ; Fig. 2A,B,D,E View Fig ), or nearly articulate with one another and be equal to the length of the palatine process ( Fr. fissilis and Fr. ulei ; Fig. 2C, F View Fig ). The dentigerous processes are large and horizontal ( Fr. fissilis , Fr. ohausi Fr. izecksohni , and Fr. ulei ; Fig. 2B,C,E,F View Fig ), or diagonally oriented ( Fr. goeldii and Fr. tonimi ; Fig. 2A,D View Fig ). Each process has 5–7 teeth and are located anterior to the neopalatines ( Fig. 2 View Fig ).
Premaxillae. This pair of dermal bones completes the maxillary arcade anteriorly ( Figs. 1–3 View Fig View Fig View Fig ). In frontal view, each premaxilla has an inverted T-shape and is separated from its counterpart by connective tissue. The pars dentalis of each premaxilla ( Fig. 2 View Fig ) bears 6 ( Fr. fissilis ), 7 ( Fr. izecksohni ), 8 ( Fr. ulei ), 8–11 ( Fr. goeldii ), 11 ( Fr. tonimi ), or 15 ( Fr. ohausi ) teeth and posterolaterally articulates with the anterior end of the pars dentalis of the maxilla. In frontal view, the longitudinal axes of the alary processes diverge anterolaterally from one another in frontal view. In lateral aspect ( Fig. 3 View Fig ), the alary processes are convex anteriorly ( Fig. 3 View Fig ). The distal ends of each pars palatina are acuminate and narrowly separated from one another ( Fig. 2 View Fig ).
Maxillae. This pair of dermal bones composes most of the upper jaw between the premaxillae and the quadratojugals ( Figs. 2 View Fig and 3 View Fig ). The anterior end laterally overlaps the posterolateral end of the premaxilla ( Figs. 2 View Fig and 3 View Fig ). The posterior end is slender and acuminate and broadly separated from the quadratojugal ( Figs. 2 View Fig and 3 View Fig ). The pars facialis is high, thin and located on the anterior half of the maxilla ( Fig. 2 View Fig ). In all species of Fritziana except Fr. goeldii ( Figs. 1A View Fig and 3A View Fig ), a short dorsal process (preorbital) of the pars facialis extends toward the maxillary process of the nasal; the processes articulate in Fr. izecksohni ( Figs. 1E View Fig and 3E View Fig ), Fr. fissilis ( Figs. 1C View Fig and 3C View Fig ), Fr. tonimi ( Figs. 1C View Fig and 3C View Fig ), and Fr. ulei ( Figs. 1F View Fig and 3F View Fig ), and Fr. ohausi (ZUFRJ 597, 12416) and are separated in Fr. ohausi (ZUFRJ 12417; Figs. 1B View Fig and 3B View Fig ).
Quadratojugals ( Figs. 1–3 View Fig View Fig View Fig ). These are posterior dermal components of the upper jaw. The quadratojugals are small nubs of bone that articulate with the ventral arm of the squamosal lateral to the palatoquadrate cartilage. When the upper jaw is incomplete, the quadratojugal usually has a ligamentous connection to the posterior end of the maxilla.
Pterygoids ( Figs. 2 View Fig and 3 View Fig ). This pair of triradiate dermal bones braces the maxillae (anteriorly) against the otic capsule (posteromedially) and palatoquadrate cartilage (posterolaterally). The anterior ramus is the longest of the three rami in all species of Fritziana ( Fig. 2 View Fig ). The medial and posterior rami are approximately the same length in all species of Fritziana except Fr. tonimi and Fr. ulei ( Fig. 2 D. F View Fig ), in which the medial ramus is shorter than the posterior ramus. The anterior ramus of the pterygoid is long, slender, and semi-cylindrical around the pterygoid cartilage; the ramus has an acuminate terminus along the lingual side of the posterior maxillary cartilage that extends along the inner surface of the maxilla ( Fig. 2 View Fig ). The short, laminar medial ramus has a truncate end that terminates on the anterior surface of the otic capsule. The short posterior ramus extends to the alar process of parasphenoid not reaching it ( Fig. 2 View Fig ). It extends to the ventromedial surface of the palatoquadrate cartilage, bracing the angle of the jaw (i.e., palatoquadrate cartilage, pars articularis, ventral arm of the squamosal, and quadratojugal) against the neurocranium.
Squamosals ( Figs. 1 View Fig and 3 View Fig ). This pair of dermal bones suspends the upper jaw from the dorsal margin of the posterolateral neurocranium, the crista parotica. In lateral aspect ( Fig. 3 View Fig ), the squamosals are triradiate and T-shaped. The dorsal head of the squamosal “T” is composed of a short anterior zygomatic ramus that extends along the posterior margin of the orbit toward ( Fig. 1 View Fig ) ( Fig. 3 View Fig ), and the posterior otic ramus that lies adjacent to the lateral margin of the crista parotica ( Fig. 1 View Fig ). The ventral ramus extends from the head of the bone over the lateral surface of the palatoquadrate cartilage and has a broad, truncate articulation with the quadratojugal ventrally ( Fig. 3 View Fig ).
Mandible ( Fig. 4A View Fig ). The lower jaw comprises three bones—the anterior mentomeckelian, and the dermal dentary and angulosplenial—that flank the lateral and lingual surfaces of Meckel’ s cartilage, respectively. The symphyseal mentomeckelians are separated from one another by connective tissue, and in frontal view, each bone has a sharp anterior point. The bones are fused to the dentaries laterally. The dentary is less than half the length of the angulosplenial bone ( Fig. 4A View Fig ). The angulosplenial bone composes about 80% of the length of the lower jaw. Posteriorly, it bears a poorly developed coronoid process and articulates with the pars articularis of the upper jaw.
Auditory region ( Fig. 2 View Fig ). The ear is complete, with an ossified plectrum (or columella) and operculum. The slender, cylindrical plectrum extends from the fenestra ovalis to the tympanum, and the conical operculum lies in the fenestra ovalis adjacent to the prootic bone.
Hyolaryngeal apparatus. The hyoid plate ( Fig. 4A View Fig ) is twice as wide as long, with a deep hyoglossal sinus. The alary processes are thin, perpendicular to the axial axis of the hyoid plate, clearly oriented forward and distally expanded ( Fr. goeldii and Fr. tonimi ) or not ( Fr. ohausi ). The boundaries between the hyoid plate and the posteromedial processes are distinct. The hyale are thin and curved. The distal ends are contiguous in cartilage with the anteroventral surface of the otic capsule. The posterolateral processes of the hyoid extend posterolaterally from the posterolateral margin of the hyoid plate. These cartilaginous processes may be: small, extending less than one-fifth the length of the bony posteromedial process ( Fr. ohausi ); moderate in length, extending between one-fifth and one-third the length of the posteromedial process ( Fr. goeldii ; Fig. 4A View Fig ); or long, extending almost two-thirds the length of the bone ( Fr. tonimi ). The distal ends of the bony posteromedial processes of the hyoid are expanded and terminate distally in cartilage.
The arytenoid cartilages are narrowly separated from each other ( Fig. 4A View Fig ). The cricoid cartilage bears a short oesophageal process, and the lateral process of the cricoid fits over the end of the posteromedial process and is laterally contiguous with it ( Fig. 4A View Fig ).
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